there is a very good tutorial on posing over at CuriousLabs. depending on what you want, you can browse the freestuff here and at runtimedna , and try the realdeals at poserpros. you can do a lot with the poser5 people so you don't have to start collecting items immediately. Just see what you lack, and when it hinders your inspiration, you can spend some money. Just never forget that the biggest market for Poser is not the application itself, but the items you buy for it. my suggestion is to start with only one figure and eventually a background behind it (like a wall). First try to get a good pose, then set a good white lighting (shadows)and next add textures and materials. Finally you can evt add colour to some of your lights to create more of an atmosphere.

I have tried prudent planning long enough. From now I'll be mad. (Rumi)